perf: expose and reduce message publish latency

server/main.go

@@ -182,6 +182,8 @@ var globals struct {
 	tlsRedirectHTTP string
 	// Maximum message size allowed from peer.
 	maxMessageSize int64
+	// Log complete client packets. Disabled by default because it is expensive on the publish hot path.
+	logClientPackets bool
 	// Maximum number of group topic subscribers.
 	maxSubscriberCount int
 	// Maximum number of indexable tags.
@@ -335,6 +337,8 @@ type configType struct {
 	// Maximum message size allowed from client. Intended to prevent malicious client from sending
 	// very large files inband (does not affect out of band uploads).
 	MaxMessageSize int `json:"max_message_size"`
+	// Log every decoded client packet. Intended only for short diagnostic sessions.
+	LogClientPackets bool `json:"log_client_packets"`
 	// Maximum number of group topic subscribers.
 	MaxSubscriberCount int `json:"max_subscriber_count"`
 	// Masked tags namespaces: tags immutable on User (mask), mutable on Topic only within the mask.
@@ -670,6 +674,7 @@ func main() {
 	if globals.maxMessageSize <= 0 {
 		globals.maxMessageSize = defaultMaxMessageSize
 	}
+	globals.logClientPackets = config.LogClientPackets
 	// Maximum number of group topic subscribers
 	globals.maxSubscriberCount = config.MaxSubscriberCount
 	if globals.maxSubscriberCount <= 1 {